Babesia Microti Research Articles

Comparative ecological analysis and predictive modeling of tick-borne pathogens.

Tick-borne diseases constitute the predominant vector-borne health threat in North America. Recent observations have noted a significant expansion in the range of the black-legged tick (Ixodes scapularis Say, Acari: Ixodidae), alongside a rise in the incidence of diseases caused by its transmitted pathogens: Borrelia burgdorferi Johnson (Spirochaetales: Spirochaetaceae), Babesia microti Starcovici (Piroplasmida: Babesiidae), and Anaplasma phagocytophilium Zhu (Rickettsiales: Anaplasmataceae), the causative agents of Lyme disease, babesiosis, and anaplasmosis, respectively. Prior research identified environmental features that influence the ecological dynamics of I. scapularis and B. burgdorferi that can be used to predict the distribution and abundance of these organisms, and thus Lyme disease risk. In contrast, there is a paucity of research into the environmental determinants of B. microti and A. phagocytophilium. Here, we use over a decade of surveillance data to model the impact of environmental features on the infection prevalence of these increasingly common human pathogens in ticks across New York State (NYS). Our findings reveal a consistent northward and westward expansion of B. microti in NYS from 2009 to 2019, while the range of A. phagocytophilum varied at fine spatial scales. We constructed biogeographic models using data from over 650 site-year visits and encompassing more than 250 environmental variables to accurately forecast infection prevalence for each pathogen to a future year that was not included in model training. Several environmental features were identified to have divergent effects on the pathogens, revealing potential ecological differences governing their distribution and abundance. These validated biogeographic models have applicability for disease prevention efforts.

Molecular detection of Coxiella burnetii in blood and hard tick-infested Egyptian camels and the possibility of coinfections

Coxiella burnetii, a bacterium that causes Q fever. It can infect mammals and has a global geographical distribution, but data on its occurrence in Egyptian dromedaries and the associated ticks are limited. Therefore, this study aims to detect C. burnetii in the blood of infested camels and associated ticks collected from Egypt by using molecular techniques and to examine the possibility of coinfections with C. burnetii. A total of 133 blood samples and 1260 hard ticks infesting these camels were collected from Egyptian slaughterhouses. Nested PCR and sequencing were used based on the IS1111 gene for molecular detection of C. burnetii. The identification of tick species at the molecular level was performed using the COX1 gene. C. burnetii was detected in Hyalomma (H) dromedarii, H. anatolicum, H. marginatum, Amblyomma (Am) lipidium, and Am. cohaerens with an overall prevalence rate of 1.3% (16/1260), while in the camel blood samples, it was 15.8% (21/133). Out of C. burnetii-positive ticks, there were double infections by Borrelia species and C. burnetii in H. dromedarii and Am. lipidium and triple infections at one Am. cohaerens tick (C. burnetii, Borrelia spp., and Babesia microti). In addition, two positive camel blood samples were found to carry C. burnetii with Borrelia spp. Our research findings indicate the presence of Coxiella burnetii among camels and their associated ticks in Egypt and emphasize the potential of having coinfection. To prevent the transmission of this infection to other animal species or humans, appropriate control measures should be implemented.

Surveillance of tick-borne pathogens present in ticks (Acari: Ixodidae) removed from companion animals in Louisiana, USA.

Current knowledge of tick distribution and tick-borne pathogen presence across Louisiana is limited. Collaborating with veterinarians across the state, ticks removed from companion animals were recovered and assessed for the presence of zoonotic pathogens. A large number of ticks (n = 959) were removed from companion animals and subsequently screened using qPCR for Anaplasma phagocytophilum, Babesia microti, Borrelia burgdorferi, Bartonella henselae, Ehrlichia chaffeensis, and spotted fever group Rickettsia. Five different tick species, Ixodes scapularis (54.5%), Amblyomma americanum (18.4%), Amblyomma maculatum (12.5%), Dermacentor variabilis (11.2%), and Rhipicephalus sanguineus (0.3%) from different regions of Louisiana were collected from October 2018 to July 2019. There were 15 PCR-positive ticks for Rickettsia parkeri (1.6% prevalence), and four ticks were positive for Ehrlichia chaffeensis (0.4% prevalence). This survey identifies ticks and tick-borne pathogens associated with companion animals and areas for future active surveillance.

B-206 Tick-borne disease molecular testing positivity and coinfection incidence in the northeastern united states: 2021-2023

Abstract Background The CDC estimates that Lyme disease affects hundreds of thousands of people each year in the United States. Tick-borne diseases caused by pathogens such as Anaplasma phagocytophilum, Babesia microti, Ehrlichia chaffeensis, and species of Borrelia follow a seasonal pattern due to the life cycle of disease-carrying ticks. In endemic areas, like the northeastern United States, the risk of coinfection by multiple tick-borne disease pathogens is higher and can complicate patient treatment. For example, while Anaplasma and Borrelia can be treated with doxycycline a Babesia coinfection would not be resolved with this medication. In this study, we performed a retrospective analysis of tick-borne disease molecular testing results to monitor positivity rates and incidence of coinfection. Methods This retrospective analysis included whole blood specimens submitted to a regional clinical laboratory in the northeastern United States for tick-borne disease molecular testing. Test results from 2021-2023 were analyzed for positivity rate trends and coinfection incidence. DNA was isolated from patient specimens and tested using laboratory developed real-time Taq polymerase PCR assays. Results Positivity rates for all tick-borne disease pathogens studied followed typical seasonal patterns (Table). Beginning in the early spring, as nymphs ended their dormancy and began to feed, infection rates of tick-borne disease climbed. Infections peaked in mid-summer and remained elevated through late autumn. For Anaplasma, a biphasic pattern was observed, with a smaller peak in late autumn when adult ticks are most active. Coinfections with Anaplasma and Babesia were observed in 136 specimens, while coinfections with Borrelia and Babesia were observed in 145 specimens. Conclusions Positivity rates for tick-borne disease pathogens followed expected seasonal patterns in the northeastern US. The incidence of coinfections involving Babesia microti highlights the importance of properly identifying tick-borne infections given the different treatment regimens indicated.

Tumor Necrosis Factor Receptors and C-C Chemokine Receptor-2 Positive Cells Play an Important Role in the Intraerythrocytic Death and Clearance of Babesia microti.

Babesia microti is an Apicomplexan parasite that infects erythrocytes and causes the tick-transmitted infection, babesiosis. B. microti can cause a wide variety of clinical manifestations ranging from asymptomatic to severe infection and death. Some risk factors for severe disease are well-defined, an immune compromised state, age greater than 50, and asplenia. However, increasing cases of severe disease and hospitalization in otherwise healthy individuals suggests that there are unknown risk factors. The immunopathology of babesiosis is poorly described. CD4+ T cells and the spleen both play a critical role in parasite clearance, but few other factors have been found that significantly impact the course of disease. Here, we evaluated the role of several immune mediators in B. microti infection. Mice lacking TNF receptors 1 and 2, the receptors for TNFα and LTα, had a higher peak parasitemia, reduced parasite killing in infected red blood cells (iRBCs), and delayed parasite clearance compared to control mice. Mice lacking CCR2, a chemokine receptor involved in the recruitment of inflammatory monocytes, and mice lacking NADPH oxidase, which generates superoxide radicals, demonstrated reduced parasite killing but had little effect on the course of parasitemia. These results suggest that TNFR-mediated responses play an important role in limiting parasite growth, the death of parasites in iRBCs, and the clearance of iRBCs, and that the parasite killing in iRBCs is being primarily mediated by ROS and inflammatory monocytes/macrophages. By identifying factors involved in parasite killing and clearance, we can begin to identify additional risk factors for severe infection and newer therapeutic interventions.

Molecular prevalence, epidemiology, and phylogenetic analysis of Babesia microti in dogs with a note on its impact on host hematological profile

Babesia (B.) microti is an intra-erythrocytic protozoan parasite that infects humans as well as domestic and wild animals. Prevalence of B. microti was investigated in 654 apparently healthy dogs belonging to 55 different breeds from three districts in Punjab province (Muzaffargarh, Bahawalpur and Jhang) and two districts in Khyber Pakhtunkhwa province (Dir Upper and Charsadda) in Pakistan. The hematological profile of dogs, risk factors associated with the infection and phylogenetic diversity of the detected isolates were also evaluated. In total, 29 blood samples (4 %) scored PCR positive. Sanger sequencing of partial 18S rRNA gene confirmed the presence of B. microti. The phylogenetic analysis of the sequences based on the 18S rRNA gene displayed global phylogenetic similarity with the isolates that were previously documented from Russia, France, Poland, Spain, China, Japan and USA. The infection rate was consistent across different sampling sites and dog breeds. Sex or presence of ectoparasites on dog was also not associated with B. microti prevalence. Babesia microti infected dogs had elevated red cell distribution width-coefficient of variation (%) than uninfected animals. This study presents updated data about the prevalence of B. microti among local Pakistani dogs and will be helpful in designing control strategies against this tick-borne pathogen as the tick infesting a B. microti infected dog may transmit this parasites to human as well.

Pathogens detected in ticks (Ixodes ricinus) feeding on red squirrels (Sciurus vulgaris) from city parks in Warsaw

The European red squirrel (Sciurus vulgaris) is a common host for Ixodes ricinus ticks in urban and rural habitats, however, studies on ticks and tick-borne pathogens (TBPs) of squirrels have not been conducted in Poland yet. Thus, the aims of the current study were to assess and compare the prevalence and abundance of ticks on red squirrels trapped at two sites in the Warsaw area (in an urban forest reserve and an urban park) and using molecular tools, to assess the genetic diversity of three pathogens (Borrelia burgdorferi sensu lato, Rickettsia and Babesia spp.) in I. ricinus ticks collected from squirrels. For the detection of Rickettsia spp. a 750 bp long fragment of the citrate synthase gltA gene was amplified; for B. burgdorferi s.l. 132f/905r and 220f/824r primers were used to amplify the bacterial flaB gene fragments (774 and 605 bp, respectively) and for Babesia spp., a 550 bpfragment of 18S rRNA gene was amplified. In total, 91 red squirrels were examined for ticks. There were differences in tick prevalence and mean abundance of infestation in squirrels from the urban forest reserve and urban park. Three species of B. burgdorferi s.l., Rickettsia spp., and Babesia microti were detected in ticks removed from the squirrels. Our results broaden knowledge of S. vulgaris as an important host for immature I. ricinus stages and support the hypothesis that red squirrels act as a reservoir of B. burgdorferi. Moreover, we conclude that red squirrels may also play a role in facilitating the circulation of other pathogens causing serious risk of tick-borne diseases in natural and urban areas.

Effects of Peromyscus spp. (Rodentia: Cricetidae) presence, land use, and ecotone on Ixodes scapularis (Acari: Ixodidae) ecology in an emergent area for tick-borne disease.

As the range of Ixodes scapularis Say expands, host abundance and land use can play important roles in regions where ticks and their associated pathogens are emerging. Small mammal hosts serve as reservoirs of tick-borne pathogens, with Peromyscus leucopus Rafinesque often considered a primary reservoir. A sympatric species Peromyscus maniculatus Wagner is also a competent reservoir and is notoriously difficult to differentiate from P. leucopus. Anthropogenic land use can alter host and habitat availability, potentially changing tick exposure risk. We tested the hypotheses that tick infestation and pathogen prevalence differ between the two Peromyscus spp. and that host-seeking I. scapularis density and pathogen prevalence differ across land use and ecotone gradients. We live trapped small mammals and collected ticks across 3 land-use classifications and ecotones in Maine, an emergent area for tick-borne disease. We tested each small mammal and tick sample for Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti. While both Peromyscus spp. serve as hosts for immature ticks, P. leucopus exhibited a higher tick infestation frequency and intensity. We did not detect any significant difference in pathogen infection prevalence between the two species. The density of I. scapularis nymphs and the density of infected nymphs did not differ significantly between land-use types, though did differ across ecotones. We also noted a significant north/south gradient, with higher tick densities and pathogen prevalence at the southern end of the study area. Our study highlights the potential variability in tick density and pathogen prevalence across fine spatial scales within an emerging region for tick-borne disease.

Comparative genome-wide identification and characterization of SET domain-containing and JmjC domain-containing proteins in piroplasms

BackgroundSET domain-containing histone lysine methyltransferases (HKMTs) and JmjC domain-containing histone demethylases (JHDMs) are essential for maintaining dynamic changes in histone methylation across parasite development and infection. However, information on the HKMTs and JHDMs in human pathogenic piroplasms, such as Babesia duncani and Babesia microti, and in veterinary important pathogens, including Babesia bigemina, Babesia bovis, Theileria annulata and Theileria parva, is limited.ResultsA total of 38 putative KMTs and eight JHDMs were identified using a comparative genomics approach. Phylogenetic analysis revealed that the putative KMTs can be divided into eight subgroups, while the JHDMs belong to the JARID subfamily, except for BdJmjC1 (BdWA1_000016) and TpJmjC1 (Tp Muguga_02g00471) which cluster with JmjC domain only subfamily members. The motifs of SET and JmjC domains are highly conserved among piroplasm species. Interspecies collinearity analysis provided insight into the evolutionary duplication events of some SET domain and JmjC domain gene families. Moreover, relative gene expression analysis by RT‒qPCR demonstrated that the putative KMT and JHDM gene families were differentially expressed in different intraerythrocytic developmental stages of B. duncani, suggesting their role in Apicomplexa parasite development.ConclusionsOur study provides a theoretical foundation and guidance for understanding the basic characteristics of several important piroplasm KMT and JHDM families and their biological roles in parasite differentiation.

Do Babesia microti Hosts Share a Blood Group System Gene Ortholog, Which Could Generate an Erythrocyte Antigen That Is Essential for Parasite Invasion?

The United States of America (US) has the highest annual number of human babesiosis cases caused by Babesia microti (Bm). Babesia, like malaria-causing Plasmodium, are protozoan parasites that live within red blood cells (RBCs). Both infectious diseases can be associated with hemolysis and organ damage, which can be fatal. Since babesiosis was made a nationally notifiable condition by the Centers for Disease Control and Prevention (CDC) in January 2011, human cases have increased, and drug-resistant strains have been identified. Both the Bm ligand(s) and RBC receptor(s) needed for invasion are unknown, partly because of the difficulty of developing a continuous in vitro culture system. Invasion pathways are relevant for therapies (e.g., RBC exchange) and vaccines. We hypothesize that there is at least one RBC surface antigen that is essential for Bm invasion and that all Bm hosts express this. Because most RBC surface antigens that impact Plasmodium invasion are in human blood group (hBG) systems, which are generated by 51 genes, they were the focus of this study. More than 600 animals with at least one hBG system gene ortholog were identified using the National Center for Biotechnology Information (NCBI) command-line tools. Google Scholar searches were performed to determine which of these animals are susceptible to Bm infection. The literature review revealed 28 Bm non-human hosts (NHH). For 5/51 (9.8%) hBG system genes (e.g., RhD), no NHH had orthologs. This means that RhD is unlikely to be an essential receptor for invasion. For 24/51 (47.1%) hBG system genes, NHH had 4-27 orthologs. For the ABO gene, 15/28 NHH had an ortholog, meaning that this gene is also unlikely to generate an RBC antigen, which is essential for Bm invasion. Our prior research showed that persons with blood type A, B, AB, O, RhD+, and RhD- can all be infected with Bm, supporting our current study's predictions. For 22/51 (43.1%) hBG system genes, orthologs were found in all 28 NHH. Nineteen (37.3%) of these genes encode RBC surface proteins, meaning they are good candidates for generating a receptor needed for Bm invasion. In vitro cultures of Bm, experimental Bm infection of transgenic mice (e.g., a CD44 KO strain), and analyses of Bm patients can reveal further clues as to which RBC antigens may be essential for invasion.

Identification of Babesia microti immunoreactive antigens by phage display cDNA screen.

Human babesiosis is a malaria-like illness caused by protozoan parasites of the genus Babesia. Babesia microti is responsible for most cases of human babesiosis in the United States, particularly in the Northeast and the Upper Midwest. Babesia microti is primarily transmitted to humans through the bite of infected deer ticks but also through the transfusion of blood components, particularly red blood cells. There is a high risk of severe and even fatal disease in immunocompromised patients. To date, serology testing relies on an indirect immunofluorescence assay that uses the whole Babesia microti antigen. Here, we report the construction of phage display cDNA libraries from Babesia microti-infected erythrocytes as well as human reticulocytes obtained from donors with hereditary hemochromatosis. Plasma samples were obtained from patients who were or had been infected with Babesia microti. The non-specific antibody reactivity of these plasma samples was minimized by pre-exposure to the human reticulocyte library. Using this novel experimental strategy, immunoreactive segments were identified in three Babesia microti antigens termed BmSA1 (also called BMN1-9; BmGPI12), BMN1-20 (BMN1-17; Bm32), and BM4.12 (N1-15). Moreover, our findings indicate that the major immunoreactive segment of BmSA1 does not overlap with the segment that mediates BmSA1 binding to mature erythrocytes. When used in combination, the three immunoreactive segments form the basis of a sensitive and comprehensive diagnostic immunoassay for human babesiosis, with implications for vaccine development.

Prevalence and molecular detection of Babesia microti in rodents in Southeastern Shanxi, China.

Babesia is a tick-transmitted parasite that infects wild and domestic animals, causes babesiosis in humans, and is an increasing public health concern. Here, we investigated the prevalence and molecular characteristics of Babesia infections in the rodents in Southeastern Shanxi, China. Small rodents were captured, and the liver and spleen tissues were used for Babesia detection using traditional PCR and sequencing of the partial 18S rRNA gene. The analysis revealed that 27 of 252 small rodents were positive for Babesia, with an infection rate of 10.71%. The infection rates in different sexes and rodent tissues were not statistically different, but those in different rodent species, habitats, and sampling sites were statistically different. The highest risk of Babesia infection was observed in Niviventer confucianus captured from the forests in Huguan County. Forty-three sequences from 27 small rodents positive for Babesia infection were identified as Babesia microti, including 42 sequences from 26 N. confucianus, and one sequence from Apodemus agrarius. Phylogenetic analysis showed that all sequences were clustered together and had the closest genetic relationship with Babesia microti strains isolated from Rattus losea and N. confucianus in China, and belonged to the Kobe-type, which is pathogenic to humans. Compared to other Kobe-type strains based on the nearly complete 18S rRNA gene, the sequences obtained in this study showed the difference by 1-3 bp. Overall, a high prevalence of Babesia microti infection was observed in small rodents in Southeastern Shanxi, China, which could benefit us to take the implementation of relevant prevention and control measures in this area.

Transcriptome study reveals tick immune genes restrict Babesia microti infection.

A systems biology approach was employed to gain insight into tick biology and interactions between vectors and pathogens. Haemaphysalis longicornis serves as one of the primary vectors of Babesia microti, significantly impacting human and animal health. Obtaining more information about their relationship is crucial for a comprehensive understanding of tick and pathogen biology, pathogen transmission dynamics, and potential control strategies. RNA sequencing of uninfected and B. microti-infected ticks resulted in the identification of 15056 unigenes. Among these, 1051 were found to be differentially expressed, with 796 being upregulated and 255 downregulated (P < 0.05). Integrated transcriptomics datasets revealed the pivotal role of immune-related pathways, including the Toll, Janus kinase/signal transducer and activator of transcription (JAK-STAT), immunodeficiency, and RNA interference (RNAi) pathways, in response to infection. Consequently, 3 genes encoding critical transcriptional factor Dorsal, Relish, and STAT were selected for RNAi experiments. The knockdown of Dorsal, Relish, and STAT resulted in a substantial increase in Babesia infection levels compared to the respective controls. These findings significantly advanced our understanding of tick-Babesia molecular interactions and proposed novel tick antigens as potential vaccine targets against tick infestations and pathogen transmission.

Tafenoquine for Relapsing Babesiosis: A Case Series.

Relapsing babesiosis often occurs in highly immunocompromised patients and has been attributed to the acquisition of resistance against drugs commonly used for treatment such as atovaquone, azithromycin, and clindamycin. Tafenoquine, which is approved for malaria prophylaxis and presumptive antirelapse treatment of Plasmodium vivax malaria, has shown activity against Babesia microti in several animal models of acute infection and in a single human case of relapsing babesiosis. Here, we report 5 cases of relapsing babesiosis treated with tafenoquine, including the previous case, and begin to define the conditions for optimal use of tafenoquine in relapsing babesiosis. A definitive diagnosis of babesiosis was made by microscopic examination of Giemsa-stained thin blood smears or a real-time polymerase chain reaction (PCR) that targets the parasite 18S rRNA gene. Clearance of B. microti infection was ascertained by use of blood smear and real-time PCR. Tafenoquine was initiated with a loading dose of 600 mg. A weekly maintenance dose consisted of 200 mg or 300 mg; the lower dose was associated with a delayed clearance of B. microti. In 2 cases, all antimicrobial agents but tafenoquine were discontinued prior to clearance of infection. In 2 other cases, clearance was achieved while tafenoquine was administered along with other antimicrobial agents. In 3 of these 4 cases, tafenoquine was used in combination with atovaquone-proguanil. Other agents included atovaquone, azithromycin, and/or clindamycin. In 1 case, tafenoquine was administered alone and failed to prevent relapse. Tafenoquine can be a useful adjunct for the treatment of highly immunocompromised patients experiencing relapsing babesiosis caused by B. microti.

Geographic range and minimum infection rate of Borrelia burgdorferi, Anaplasma phagocytophilum, Babesia microti, and Borrelia miyamotoi in Ixodes scapularis (Acari: Ixodidae) ticks in Manitoba, Canada from 1995 to 2017.

The expanding geographical range of blacklegged ticks (BLTs), Ixodes scapularis, and its ability to transmit Borrelia burgdorferi, Anaplasma phagocytophilum, Babesia microti, and Borrelia miyamotoi poses an emerging public health risk. Our study determined the geographic distribution and the minimum infection rate (MIR) of B. burgdorferi-, A. phagocytophilum-, Ba. microti-, and B. miyamotoi-infected BLTs in Manitoba submitted to the Public Health Agency of Canada's passive tick surveillance programme from 1995 to 2017. Regression models were used to test the association of the MIR by year for each pathogen. Ticks were tested using PCR for B. burgdorferi since 1995, A. phagocytophilum since 2006, and Ba. microti and B. miyamotoi since 2013. The global positioning system coordinates of infected and uninfected ticks submitted during the surveillance period were plotted on a map of Manitoba using ArcGIS Pro version 3.1.2 to detect changes in the geographic distribution of ticks over time. The overall MIR for B. burgdorferi was 139.7 (95% confidence interval [CI]: 129.0-150.5) per 1000 BLTs; however, it varied over time. After remaining stable from 1995 to 2005, the MIR increased by 12.1 per 1000 BLTs per year from 2005 to 2017 (95% CI: 7.0%-17.2%, p-value <0.01). The geographic distribution of B. burgdorferi-infected BLTs was centred around Winnipeg, Manitoba, and spread outward from this locality. The MIRs of A. phagocytophilum, Ba. microti, and B. miyamotoi were 44.8 per 1000 BLTs (95% CI: 38.1-51.6), 10.8 (95% CI: 6.6-15.0), and 5.2 (95% CI: 2.3-8.1) per 1000 BLTs, respectively, and showed no significant change over time. Passive surveillance revealed the presence of A. phagocytophilum-, Ba. microti-, and B. miyamotoi-infected BLTs in southern Manitoba and revealed an increased risk of exposure to B. burgdorferi-infected BLTs due to the increasing geographic range and MIR.

Potential drivers of vector-borne pathogens in urban environments: European hedgehogs (Erinaceus europaeus) in the spotlight

Vector-borne diseases (VBDs) are considered as (re-)emerging, but information on the transmission cycles and wildlife reservoirs is often incomplete, particularly with regard to urban areas. The present study investigated blood samples from European hedgehogs (Erinaceus europaeus) presented at wildlife rehabilitation centres in the region of Hanover. Past exposure to B. burgdorferi sensu lato (s.l.) and tick-borne encephalitis virus (TBEV) was assessed by serological detection of antibodies, while current infections with Borrelia spp., Anaplasma phagocytophilum, Rickettsia spp., Neoehrlichia mikurensis, Bartonella spp., Babesia spp. and Spiroplasma ixodetis were investigated by (q)PCR. Of 539 hedgehogs tested for anti-Borrelia antibodies, 84.8% (457/539) were seropositive, with a higher seropositivity rate in adult than subadult animals, while anti-TBEV antibodies were detected in one animal only (0.2%; 1/526). By qPCR, 31.2% (168/539) of hedgehog blood samples were positive for Borrelia spp., 49.7% (261/525) for A. phagocytophilum, 13.0% (68/525) for Bartonella spp., 8.2% for S. ixodetis (43/525), 8.0% (42/525) for Rickettsia spp. and 1.3% (7/525) for Babesia spp., while N. mikurensis was not detected. While further differentiation of Borrelia spp. infections was not successful, 63.2% of the A. phagocytophilum infections were assigned to the zoonotic ecotype I and among Rickettsia spp. infections, 50.0% to R. helvetica by ecotype- or species-specific qPCR, respectively. Sequencing revealed the presence of a Rickettsia sp. closely related to Rickettsia felis in addition to a Bartonella sp. previously described from hedgehogs, as well as Babesia microti and Babesia venatorum. These findings show that hedgehogs from rehabilitation centres are valuable sources to identify One Health pathogens in urban areas. The hedgehogs are not only exposed to pathogens from fleas and ticks in urban areas, but they also act as potent amplifiers for these vectors and their pathogens, relevant for citizens and their pets.

Great genetic diversity of vector-borne bacteria and protozoan in wild rodents from Guangxi, China.

Rodents are recognized as the hosts of many vector-borne bacteria and protozoan parasites and play an important role in their transmission and maintenance. Intensive studies have focused on their infections in vectors, especially in ticks, however, vector-borne bacterial and protozoan infections in rodents are poorly understood although human cases presenting with fever may due to their infection have been found. From May to October 2019, 192 wild rodents were trapped in wild environment of Guangxi Province, and the spleen samples were collected to reveal the presence of vector-borne bacterial and protozoan infections in them. The microorganisms in rodents were identified by detecting their DNA using (semi-)nested PCR. All the PCR products of the expected size were subjected to sequencing, and then analyzed by BLASTn. Furthermore, all the recovered sequences were subjected to nucleotide identity and phylogenetic analyses. As a result, 192 rodents representing seven species were captured, and Bandicota indica were the dominant species, followed by Rattus andamanensis. Based on the (semi-)nested PCR, our results suggested that Anaplasma bovis, Anaplasma capra, Anaplasma ovis, Anaplasma phagocytophilum, "Candidatus Neoehrlichia mikurensis", "Candidatus E. hainanensis", "Candidatus E. zunyiensis", three uncultured Ehrlichia spp., Bartonella coopersplainsensis, Bartonella tribocorum, Bartonella rattimassiliensis, Bartonella silvatica, two uncultured Bartonella spp., Babesia microti and diverse Hepatozoon were identified in six rodent species. More importantly, six species (including two Anaplasma, two Bartonella, "Ca. N. mikurensis" and Bab. microti) are zoonotic pathogens except Anaplasma bovis and Anaplasma ovis with zoonotic potential. Furthermore, dual infection was observed between different microorganisms, and the most common type of co-infection is between "Ca. N. mikurensis" and other microorganisms. Additionally, potential novel Bartonella species and Hepatozoon species demonstrated the presence of more diverse rodent-associated Bartonella and Hepatozoon. The results in this work indicated great genetic diversity of vector-borne infections in wild rodents, and highlighted the potential risk of human pathogens transmitted from rodents to humans through vectors.

Unrevealing the therapeutic potential of artesunate against emerging zoonotic Babesia microti infection in the murine model.

Babesiosis, a zoonotic blood protozoal disease, threatens humans and animals and is difficult to treat due to growing antimicrobial resistance. The study aimed to investigate the therapeutic efficacy of artesunate (AS), a well-known derivative of artemisinin, against Babesia microti (B. microti) using a murine infection model. Male BALB/c mice (6 weeks old; 15 per group) were chosen and randomly divided into 1) the control group, 2) the B. microti group, and 3) the B. microti + artesunate treatment groups. AS treatment at 2 mg/kg, 4 mg/kg, and 8 mg/kg of body weight significantly (p < 0.05) reduced the B. microti load in blood smears in a dose-dependent manner. Additionally, AS treatment mitigated the decrease in body weight and restored the normal state of the liver and spleen viscera index compared to the B. microti-infected group after 28 days. Hematological analysis revealed significant increases in RBC, WBC, and PLT counts post-AS treatment compared to the B. microti-infected group. Furthermore, AS administration resulted in significant reductions in total protein, bilirubin, ALT, AST, and ALP levels, along with reduced liver and spleen inflammation and lesions as observed through histopathological analysis. AS also elicited dose-dependent changes in mRNA and protein expression levels of apoptotic, proinflammatory, and anti-inflammatory cytokines in the liver compared to the control and B. microti-infected groups. Immunolabeling revealed decreased expression of apoptotic and inflammation-related proteins in AS-treated hepatic cytoplasm compared to the B. microti-infected group. AS also in dose-dependent manner decreased apoptotic protein and increased Bcl-2. Overall, these findings underscore the potential of AS as an anti-parasitic candidate in combating B. microti pathogenesis in an in vivo infection model, suggesting its promise for clinical trials as a treatment for babesiosis.

The effect of forest structural complexity on tick-borne pathogens in questing ticks and small mammals

Forest management is increasingly focused on enhancing structural complexity. An increase in structural complexity is assumed to increase the abundance and diversity of fauna, including vertebrates. This faunal assemblage serves, in turn, as host community for a suite of vectors and their pathogens, so that structural complexity may cascade through a network of interactions in forest ecosystems. Here we use a network of 19 forest plots representing a gradient of structural complexity and dominant tree species (oak, beech, poplar) to test two hypotheses on the effect of structural complexity on the prevalence of tick-borne pathogens. Our first hypothesis is that tick densities will increase with increasing structural complexity, assuming that each life stage has higher chances of finding a suitable host. The second hypothesis is that the pathogen prevalence in ticks and small mammals decreases (cf. dilution hypothesis) or increases (cf. amplification hypothesis) with increasing structural complexity. These expectations are tested through a community-level analysis, looking at twelve pathogens: seven genospecies of Borrelia (B. afzelii, B. bavariensis, B. garinii, B. burgdorferi sensu stricto, B. spielmanii, B. valaisiana and B. miyamotoi), Babesia s.s., Babesia microti, Anaplasma phagocytophilum, Rickettsia helvetica and Spiroplasma ixodetes. We found that more structurally complex forests have a higher density of questing nymphs (in June and July, during the peak of nymph activity). We did not find a clear change in pathogen prevalence with increasing structural complexity in ticks, wood mice and bank vole; the effect was different for the different pathogens and between the different dominant tree species. No clear co-occurrence patterns of pathogens were found. The density of infected nymphs and thus the disease risk is higher in more complex forests. A potential solution is to focus on decreasing the human-tick interactions in forests instead of trying to decrease the number of questing ticks.

Antibody-blocking of a tick transporter impairs Anaplasma phagocytophilum colonization in Haemaphysalis longicornis ticks

The invasive Asian longhorned tick Haemaphysalis longicornis that vectors and transmits several animal pathogens is significantly expanding in the United States. Recent studies report that these ticks also harbor human pathogens including Borrelia burgdorferi sensu lato, Babesia microti, and Anaplasma phagocytophilum. Therefore, studies that address the interactions of these ticks with human pathogens are important. In this study, we report the characterization of H. longicornis organic anion-transporting polypeptides (OATPs) in interactions of these ticks with A. phagocytophilum. Using OATP-signature sequence, we identified six OATPs in the H. longicornis genome. Bioinformatic analysis revealed that H. longicornis OATPs are closer to other tick orthologs rather than to mammalian counterparts. Quantitative real-time PCR analysis revealed that OATPs are highly expressed in immature stages when compared to mature stages of these ticks. In addition, we noted that the presence of A. phagocytophilum upregulates a specific OATP in these ticks. We also noted that exogenous treatment of H. longicornis with xanthurenic acid, a tryptophan metabolite, influenced OATP expression in these ticks. Immunoblotting analysis revealed that antibody generated against Ixodes scapularis OATP cross-reacted with H. longicornis OATP. Furthermore, treatment of H. longicornis with OATP antibody impaired colonization of A. phagocytophilum in these ticks. These results not only provide evidence that the OATP-tryptophan pathway is important for A. phagocytophilum survival in H. longicornis ticks but also indicate OATP as a promising candidate for the development of a universal anti-tick vaccine to target this bacterium and perhaps other rickettsial pathogens of medical importance.